Ternary fuel compositions containing biodiesel, plant oil and lower alcohols for feeding diesel-cycle motors

ABSTRACT

Fuel compositions based on biodiesel, lower alcohols and plant oil for feeding Diesel cycle engines, enabling more perfect burning, less emission of pollutants and less formation of internal deposits of impurities onto the inner surface of engines. Since the blends exhibit density similar to that of diesel oil, as well as chemical affinity for the latter (since it contains biodiesel, which performs the function of co-solvent), the present invention also relates to compositions of quaternary blends, that is, junction of the ternary blends proposed (biodiesel, lower alcohol and vegetable oil) with petroleum diesel in the most varied proportions. The preferred embodiment of this invention provides the replacement of fuel of non-renewable source (diesel oil) by others of renewable source, which are natural, non-toxic, biodegradable and that have excellent technical performance.

FIELD OF THE INVENTION

The present invention relates to the technology that deals with fuel compositions based on biodiesel, alcohol like anhydrous alcohol, and vegetable oil, to be applied to Diesel cycle engines. Moreover, these compositions are technologically superior to Diesel oil, since they promote more perfect burning, less emission of pollutants and less formation of impurities deposits on the internal components of engines. Alternatively, the invention also deals with compositions as described above, associated to petrodiesel, in different proportions.

BACKGROUND OF THE INVENTION

Biodiesel, a traditional substitute for diesel oil, since it has cetane number and viscosity suitable for use on Diesel cycle engines, is a very expensive product, because, besides the high price of raw material (vegetable oil), there is cost aggregation on the order of 25% in the processing phase.

On the other hand, cheaper fuels like “in natura” vegetable oils, and chiefly ethanol, exhibit technical problems when used on Diesel cycle engines. Vegetable oils, in spite of having cetane number compatible with compression ignition engines, have too high viscosity, which leads to the formation of carbon and sludge deposits on the engines, when they are used. On the other hand, ethanol has too low viscosity and cetane number, which does not meet the requirements for a good fuel for Diesel cycle.

Considering the scientific literature, the most relevant composition found out was that presented in the papers by KWANCHAREON et al, 2006; FERNANDO & HANNA, 2006; CHEN et al, 2008, which approach fuels based on ethanol, biodiesel and diesel.

From the point of view of patents, the following documents have been found:

-   -   (i) PI0605525-7a2, which presents the use of ternary blends         containing 10-30% ethanol, 20-60% biodiesel, and 30-60%         hydrotreated vegetable oil. Comparatively, the present invention         is constituted by a different composition, does not employ         hydrotreated vegetable oil, and operates with different         proportions of components, besides having a different technical         effect.     -   (ii) MU8702637-6U2, which presents the use of binary, ternary         and quaternary blends of biodiesel, vegetable oil and higher         alcohols. In this case, the present invention differs in both         composition and proportion, besides having, as an advantage, the         direct use of ethyl alcohol or methanol, among other not higher         alcohols.     -   (iii) PI0602633-8A2, which presents the a mixture of diesel with         a higher alcohol, biodiesel and vegetable oils, a more complete         combustion, reductions of particulate matter in emissions and of         carbon deposits, enhancement of fuel lubricity, maintenance of         the levels of performance and durability of the engines and of         their injection systems. In the present case, such a composition         is more complex and expensive, involving more components, so         that the present invention proves to be superior by virtue of         the fact that the mixture is obtained by means of components         that are all renewable and in smaller number, in different         proportions, besides exhibiting an excellent technical effect         with regard to energy efficiency, emission of pollutants and         deposition of impurities on the internal components of Diesel         cycle engines. One should observe that it does not need to         present an alcoholic component of the higher alcohol type         (alcohols with many carbon atoms on the chain, such as cetyl         alcohol).

In conclusion, the present invention consists in joining three renewable fuels (biodiesel, alcohol, such as anhydrous ethanol, and vegetable oil), which can be employed in a direct manner, without any previous treatment, in given proportions of interest, so as to form blends, whereby the physicochemical characteristics of each complement each other so as to compose a final fuel suitable for use on Diesel cycle engines, with excellent combustible properties.

SUMMARY OF THE INVENTION

The present invention relates to a fuel for feeding Diesel cycle engine, characterized by exhibiting the following composition:

-   -   i. alcohol, preferably of the anhydrous type, ranging from 10%         to 50% by mass;     -   ii. vegetable oil ranging from 10% to 60% by mass; and     -   iii. ethyl or methyl ester (biodiesel) ranging from 20% to 80%         by mass.

Alternatively, said composition may contain alcohol in the form of ethanol or methanol, preferably of the anhydrous type.

For certain applications, in the non-ideal embodiment, the composition may have the following form:

-   -   i. alcohol, preferably anhydrous, ranging from 10% to 50% by         mass;     -   ii. vegetable oil ranging from 10% to 60% by mass; and     -   iii. petrodiesel, biodiesel or any mixture thereof ranging from         20% to 80% by mass.

Another possible embodiment is based on the employ of the ternary mixture (biodiesel, alcohol and vegetable oil) associated to petrodiesel in any proportion.

Technically, the combustible compositions presented herein prove to be of great relevance, due to the following factors, among others reasons:

-   -   (i) decrease in the delay in ignition of the final fuel (blends         of biodiesel, alcohol, preferably anhydrous ethanol, and         vegetable oil) due to the lower flash point of alcohol and to         its greater volatility and higher cetane number of biodiesel,         which means an increase in the thermal efficiency and greater         acceleration, mainly at low rotations, due to the more intense         vaporization of the fuel used;     -   (ii) decrease in the final viscosity of the fuel used in         comparison with the use of the most varied pure vegetable oils,         which facilitates the pulverization of the fuel injected into         the combustion chamber and results in decrease or elimination of         the formation of sludge and varnish (caused by polymerization of         the fuel—coking) in the injection pump, on the injection nozzles         and inside the cylinders, besides contributing to a more         complete combustion, with the consequent increase in thermal         efficiency and reduction in emission of pollutants, among which         are nitrogen oxides, particulate matter, carbon monoxide and         free hydrocarbons;     -   (iii) lowering of the temperature of beginning of         crystallization (cloud point) of the final fuel because they         contain alcohol, preferably ethanol or methanol, in their         composition, leading to smaller start problems when such blends         are used in environments of low temperatures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows maps of miscibility for the ternary blends at different temperatures; the yellow points indicate miscible blends, and the red points indicate immiscible blends;

FIG. 2 shows thermal efficiency as a function of the load applied;

FIG. 3 shows emission of particulate matter as a function of the load applied;

FIG. 4 shows emission of particulate matter at a 5-minute collection interval, as a function of the load applied by the generator to the engine;

FIG. 5 shows emission of particulate matter collected;

FIG. 6 shows injector nozzle of the engine fed with diesel oil;

FIG. 7 shows injection nozzle of the engine fed with ternary mixture;

FIG. 8 shows the piston top of the engine fed with diesel oil;

FIG. 9 shows piston top of the engine fed with ternary mixture.

DETAILED DESCRIPTION OF THE INVENTION

The present invention consists in joining the three fuels described (biodiesel, alcohol, such as anhydrous ethanol, and vegetable oil) for the formation of blends, whereby the physicochemical characteristics of each complete each other, so as to compose a final fuel suitable for use on Diesel cycle engines.

The fuel compositions of the present invention are based on a few physicochemical properties of interest, see: (i) alcohol, preferably ethanol or methanol, is a polar substance; (ii) vegetable oil is a non-polar substance; hence (iii) the use of biodiesel as a double-solubility co-solvent agent. It is important to point out that the process of mixing the components relating to all the fuel compositions of the present invention involves the conventional association employing containers or tanks according to the following order of mixture: association of biodiesel to ethanol, followed by addition of vegetable oil, according to the proportions of interest. The mixture optionally the non-ideal embodiment, may involve the addition of petrodiesel. Moreover, it is expressed that the components cited may be associated according to various orders, in view of the cited physicochemical properties which they exhibit in terms of miscibility.

The decrease in the delay of ignition of a fuel inside the cylinder of a Diesel cycle engine implies an increase in the thermal efficiency thereof. By using blends that contain, among other fuels, anhydrous ethanol, a compound with relatively low flash point and considerable volatility, there is a higher velocity in the break of the big molecules that form the same blends, reducing the reaction time and increasing the thermal efficiency of the engine.

The presence of anhydrous ethanol and biodiesel in the proposed blends implies quite lower viscosities that those relates with pure vegetable oil, which acts as an element that attenuates or even inhibits the formation of sludge and varnishes (caused by polymerization of fuel—“coking”) in the injection pump, in the injection nozzles and in the cylinders of Diesel cycle engines; the ethanol present in the blends results in lowering the crystallization start temperature (cloud point) of the final fuel, leading to minor start problems in cold environments when such blends are used. Besides these aspects, since the blends exhibit density similar to that of diesel oil, as well as chemical affinity for the latter (because it contains biodiesel that performs the function of a co-solvent), there are possibilities of making compositions of quaternary blends, that is, joining the proposed ternary blends (biodiesel, anhydrous ethanol and vegetable oil) with petroleum diesel, in the most varied proportions.

Another great advantage of these blends relies on the fact that they are formed by compounds extracted from agricultural products and, therefore, of renewable origin, which are natural, non-toxic and biodegradable blends.

As it is known to those skilled in the art, the present-day Diesel cycle-engines have a number of drawbacks regarding both their operation and the ecological aspects. Among these drawbacks, the following can be cited:

-   -   (i) in comparison with Otto-cycle engines, they exhibit a lower         acceleration due to the low fuel-vaporization rate after         injection thereof into the combustion chamber, above all at         lower rotations;     -   (ii) high level of emission of nitrogen oxides due to the high         combustion temperatures imposed by the high compression rates of         the engines; and     -   (iii) use of fossil fuel (diesel oil), which has large carbon         chains, which leads to incomplete burning inside the cylinder         and excess emission of particulate matter.

By employing the proposed blends (biodiesel, alcohol, such asanhydrous ethanol, and vegetable oil) as fuel on Diesel cycle engines, the following advantages area achieved:

-   -   (i) total replacement of the petroleum diesel consumed by the         engine, that is, a fuel of non-renewable source (diesel oil) is         replaced by another of renewable source (blends containing         biodiesel, anhydrous ethanol and vegetable oil); in the case of         a partial replacement, one can make a composition of quaternary         mixture formed by the proposed blends and by diesel oil in the         most varied proportions;     -   (ii) decrease in the delay of ignition of the final fuel (blends         of biodiesel, anhydrous ethanol and vegetable oil) due to the         lower flash point of ethanol and its greater volatility, and to         the higher cetane number of biodiesel, which clearly implies an         increase in the thermal efficiency;     -   (iii) higher acceleration, chiefly at low rotations, by virtue         of the more intense vaporization of the fuel used;     -   (iv) decrease or elimination of the formation of sludge and         varnishes produced in the injection pump, in the injection         nozzles and inside the cylinders;     -   (v) decrease in the final viscosity of the fuel used (blends)         with respect to the use of the most varied pure vegetable oils,         facilitating the pulverization of the fuel injected into the         combustion chamber, which results in a more complete combustion,         with the consequent increase in thermal efficiency and reduction         of emission of pollutants, among them, nitrogen oxides and         particulate matter; in parallel, one can obtain lower values of         emission of carbon monoxide and of free hydrocarbons, since the         combustion is more efficient; and     -   (vi) lowering the crystallization start temperature of the fuel         (cloud point) because they have ethanol in their composition.

Therefore, the invention is based on the use of blends of renewable fuels (biodiesel, anhydrous ethanol and vegetable oil) on Diesel cycle engines, thus seeking technical, ecological and operational advantages described above. Alternatively, one can employ a composition of quaternary blends formed by the blends presented and by diesel oil in the most varied proportions.

EXAMPLES

Work 1: evaluation of performance and durability of engines fed with composition of the present invention with respect to petroleum diesel oil (B4).

One of the experiments to evaluate the proposed technology consists of the following treatments: (i) Petroleum diesel (B4); e (ii) ternary mixture: 50% biodiesel+40% anhydrous methanol+10% vegetable oil (volumetric composition). The fuels were tested in two 6-HP Diesel cycle engines (one for testing with diesel oil; the other for the mixture), and an electric energy generator and 18 150-W lamps were used for the purpose of energy consumption elements (load). FIG. 2 discloses the profile of thermal efficiency as a function of the load applied, so that one observes that the efficiency of the ternary mixture of the present invention behaves in a superior manner as compared with the control treatment (petroleum Diesel (B4)). Moreover, it was found out that the emission of particulates was of about 70% lower with the use of the ternary mixture by virtue of the replacement of the diesel oil, with big molecules and high boiling points, by: (i) ethanol, formed by a simple molecule and reduced boiling point; (ii) biodiesel, which does not contain sulfur, that shares oxygen with the carbon resulting from the partial burning.

The experiment also involved a test of durability of 150 hours on the basis of the analysis, after this period, of the following elements: injection nozzle of the engine fed with diesel oil (FIG. 6); injector nozzle of the engine fed with ternary mixture (FIG. 7); piston top of the engine fed with diesel oil (FIG. 8); piston top of the engine fed with ternary mixture (FIG. 9). As one can observe in these figures, all the components of the engine fed with the ternary mixture of the present invention were better preserved after the testing period in comparison with the correspondent components of the engine fed with petroleum Diesel (B4).

Thus, the ternary mixture determines much smaller formation of carbon residues and, as a result: (i) lower contamination of the lubricant, which enables full performance of its functions (lubrication); (ii) less wear of the internal moveable pieces of the engine.

Therefore, one concludes that the use of the renewable mixture (50-40-10) has enabled one to observe, in comparison with the use of petroleum diesel: normal functioning of the engine (without irregularities); 10% higher thermal efficiency; emission of particulate matter about 70% lower; lower internal carbonization and less wear.

Work 2: quantification of the particulate matter emitted by a Diesel cycle engine fed with ternary blends containing biodiesel, ethanol and vegetable oil.

Introduction

The emission components, of both Diesel cycle engines and Ot-to-cycle engines, may be classified into two types: those that do not cause harm to one's health (O₂, CO₂, H₂O and N₂) and those that present dangers to one's health (CO, HC, NOx, SOx and MP)⁸.

Among the latter, the particulate matter (PM) is the atmospheric pollutant that is usually most associated to adverse effects on human health.¹

In the last few decades, a great effort has been made to reduce the use of fuels derived from petroleum for generating energy and transportation throughout the world. Among the recent alternatives proposed, biodiesel and ethanol, in addition to blends containing biodiesel/diesel and alcohol/diesel, have brought much attention to the use of Diesel cycle engines, which are presented as one of the solutions, in various countries, for reducing their importation of petroleum and decrease in the emissions of pollutants.

In this context, the objective of this work was fixed on quantifying the emission of particulate matter of ternary blends⁶, composed of ethyl alcohol, biodiesel and vegetable oil on a Diesel cycle engine, having, as a standard condition, an identical engine operating on conventional diesel.

Materials and Methods

In order to carry out these tests, two stationary engines were used, which were of 4-stroke Diesel cycle engines of mark Toyama, model T70f, air cooled, with direct injection and 6-HP nominal power, one of which was supplied with only conventional diesel oil, and the other with ternary blends. Thus, each engine could be evaluated individually according to the fuel employed. In order to impart load to the engine, an electric generator of mark Bambozzi, of 10 kVA, with nominal rotation of 1,800 rpm was employed.

For comparison of the emission produced, collection of particulate matter from exhaust gases of the engines was carried out by using a circular filter with 5 cm in diameter, made from fiberglass.

The three volumetric blends of biofuels used in the tests were composed of:

-   -   a) 60% biodiesel, 20% anhydrous ethanol and 20% vegetable oil         (mixture 1);     -   b) 60% biodiesel, 30% anhydrous ethanol and 10% vegetable oil         (mixture 2);     -   c) 50% biodiesel, 40% anhydrous ethanol and 10% vegetable oil         (mixture 3).

Besides these, standard fuel (diesel oil derived from petroleum) was employed for establishing a reference.

The work procedure used was the following: first, the filters were dehydrated in an oven at 105° C. and weighed; then, they were coupled to the exhaust end, where they remained for 2, 5, 8, and 10 minutes. Then, the filters were again dehydrated and weighed, which enabled one to register the mass of retained material.

For determining the ideal collection time, a number of tests were carried out, wherein an expressive difference in amount of particulate matter between the filters exposed to exhaust gases for 2 and 5 minutes (with higher concentration of particles in the filter of longer exposure time).

With 8 and 10 minutes' collection, no difference was noticed between the material retained therein and the filters with 5 minutes' exposure. Thus, for collection of particulate matter, one adopted the standard 5-minute time.

As can be seen in FIG. 4, the results achieved by using the ternary blends of biofuels indicate an expressive reduction of the level of particulate matter emitted by the engine at rotation of 3,600 rpm (maximum rotation), with respect to conventional diesel. This behavior of emission of particulates by the engines is due to the replacement of a fuel having a long carbon chain (diesel oil), with 13 carbon atoms, on an average, and high boiling point (from 190° C. to 330° C.), by a mixture of fuels containing ethanol, more simple carbon chain and lower boiling temperature.

While the load required by the generator does not exceed 1800 Watts, the emission of PM between the fuels was similar, but as the load is raised to 2,700 Watts (which would require a larger volume of fuel injected into the combustion chamber), the amount of PM emitted by use of diesel oil was quite larger that from the burning of all the blends. In terms of numbers, one observes 28 mg emitted by diesel, whereas the ternary blends produce from 10 to 13 mg, for the maximum established load. One has also observed that the increase in the proportion of ethanol in the ternary mixture favored the drop in the emission PM, a fact that, according to Dietrich & Dindel (1983)², can be explained by the capability of ethanol to provide a more efficient combustion, which implies a reduction in the contents of non-required carbon.

The decrease in the emission of particulates was also observed in the experiments of Holmer et al (1980)⁵, who have made replacements of up to 32% of diesel oil with ethanol by resorting to the microemulsion. Similar results were achieved by Goering et al (1992)⁴, who noted suppression in the emission of smoke when they used injection of ethanol into the intake manifold or into the cylinder injector. In the same line of reasoning, Feitosa (2003)3 achieved an expressive decrease in the emission of particulates by replacing up to 50% of diesel with ethanol.

In addition to ethanol, the presence of biodiesel in the mixture also influenced positively the reduction of the emission of PM, since in the literature a number of authors have demonstrated such a fact. Blends of sunflower/diesel biodiesel (B25, B50, B75 and B100) were used by Muños et al (2004)⁷, on an automotive Diesel engine, to determine the levels of emission of pollutants. The reduction of the degree of blackening and of the specific emission of particulate matter was quite representative and favorable to the use of biodiesel, which is caused, in part, by the absence of sulfur in the biodiesel. Sulfur shares the oxygen available in the later phase of the combustion with the carbon resulting from the partial burning, in some conditions of operation of the engine, increasing the production of particulate material⁸. As a final conclusion, one can say that the results of the present work led to the confirmation that the use of the ternary blends of biofuels, in the conditions and methods of carrying out the experiment was efficient in the reduction of emission of particulate matter present in the exhaustion gases of the Diesel cycle engine under study.

Bibliography

-   1 Abbey, D. E.; Nishino, N.; Mcdonnell, W. F.; burchette, R. J.;     Knutsen, S. F.; Beeson, W. L.; Yang, J. X. Longterm inhalable     particles and other air pollutants related to mortality in     nonsmokers. American Journal of Respiration and Critical Care     Medicine 159, no. 373-382, 1999. -   2 Dietrich, W.; Bindel, H. W. H. The development of “pilot     injection” for use of alcohols on Diesel cycle engines. In; SIMPÓSIO     DE ENGENHARIA AUTOMOTIVA 1. ENCONTRO DOS CENTROS DE APOIO     TECNOLÓICO, 11. 1983, Brasililia, D F, Anais, 1983, p. 515-533. -   3 Feitosa, M. V. Development of compression ignition engine fed by     direct injection of diesel oil and by ethanol post-vaporized in the     intake manifold, 2003, 217 p. -   Dissertation (for PhD)—Escola de Engenharia de São     Carlos—Universidade de São Paulo, São Carlos. -   4 Goering, C. E.; Crowell, T. J.; Griffith, D. R.; Jarrett, Mo. W.;     Savage, L. D. Compression=—ignition, flexible-fuel engine.     Transactions of the ASAE, v. 35, n. 2, p. 423-428, 1992. -   5 Holmer, E.; Berg. P. S.; Bertilsson, B. I. The utilization of     alternative fuels in a Diesel engine using different methods.     Society of Automotive Engineers, SAE paper 800544. 1980. -   6 Kwanchareon, P.; Luengnauruemitchai, A.; Jai-in, S. Solubility of     a diesel-biodiesel-ethanol blend, its fuel properties, and its     emission characteristics from diesel engine. Fuel, v. 10, p.     1053-1061, 2006. -   7 Muños, M.; Moreno, F.; Morea, J. Emissions of an automobile diesel     engine fueled with sunflower methyl ester. Transactions of the     ASAE. V. 47. No. 1, p. 5-11, 2004. -   8 Neeft, J. P. A.; Makkeee, M.; Moulijin, J. A. Diesel particulate     emission control. Fuel processing Technology, v. 47, p. 1′-69, 1996. -   Work 3: emission of particulate matter by ternary blends containing     biodiesel, vegetable oil and ethanol: a comparison with conventional     diesel.

Summary

The objective of this study was to quantify the emission of particulate matter of ternary blends composed by alcohol, biodiesel and vegetable oil on a Diesel cycle engine, by employing an identical witness engine operating on petroleum diesel. For the comparison of the emission of the two fuels, one has collected particulate matter from the exhaust manifold of the engines by using a circular filter paper made from fiberglass. The results achieved by using the ternary blends of biofuels indicated an expressive reduction in the level of particulate matter emitted by the engine at its maximum rotation. One can conclude that with the work that the use of such ternary blends, in the conditions and methods of carrying out the experiment, was efficient in reducing the emission of particulate matter present in the exhaust gases of the Diesel cycle engine.

Introduction

Emission compounds, of both diesel engines and gasoline or mixed-fuel engines, can be classified into two groups: those that cause harm to one's health, namely: O₂, CO₂, H₂O and N₂; and those that do not present dangers to one's health, these being subdivided into compounds whose emission is regulated: namely CO, hydrocarbons (HC), nitrogen oxides (NOx), sulfur oxides (SOx) and particulate matter (PM); and those that are not under regulation yet, namely: aldehydes, ammonia, benzene, cyanides, toluene and polynuclear aromatic hydrocarbons (HPA) (NEEFT et al, 1996).

Diesel exhaust is quite complex, being composed of three phases: solids, liquids and gases (DEGOBERT, 1995). Operation in oxidizing conditions of diesel machines, which contribute to good saving of fuel, result in lower production of CO₂ in comparison with gasoline engines, in a combustion process that operates at lower temperatures, with formation and consequent emission of a smaller amount of NOx and hydrocarbons (HC). However, this process also results in high levels of emission of particulate matter (PM) and of compounds responsible for the characteristic odor of diesel emission, the emission of the latter being highly critical during operation at low temperatures (BRAUN et al, 2003).

The particulate matter produced by a diesel machine consists basically of agglomerates of carbon nuclei and of hydrocarbons, SO₃ or sulfuric acid and water, either adsorbed or condensed on these carbon nuclei (NEEFT et al, 1996; LAHAYE & EHRBURGER-DOLLE, 1994).

The carbon nuclei are primary particles, that is, small spherical units composed basically of carbon and some inorganic material with diameter ranging from 10 to 80 nm, which is equivalent to about one million atoms of this element. Hydrocarbons from incomplete combustion of diesel oil and of lubricant oil are adsorbed onto the carbon nuclei, creating in aggregates. In turn, a number of thus formed aggregates agglomerate and form secondary particles with aerodynamic diameters ranging from 100 to 1000 nm. However, 90% of the particulate matter produced by any diesel machine has an average diameter smaller than 300 nm. The agglomeration of carbon nuclei containing adsorbed HC begins in the combustion chamber and continues until exhaustion, where large hydrocarbon molecules may condense on them at the temperature that prevails in diesel exhaustion (KERMINEN et al, 1997). The final agglomeration is called “particulate matter”, or simply “particulate”.

The average basic composition of particulate matter is 70%, by mass carbon, 20% oxygen, 3% sulfur, 1.5% hydrogen, less than 1% nitrogen and about 1% trace elements. (NEEFT et al, 1996).

The particulate matter is the atmospheric pollutant that is most consistently associated to adverse effects on human health. The toxicity of the particulate matter depends on its composition and on the aerodynamic diameter. Various studies have related the continued exposure to environmental levels of particulate matter to the reduction of life expectancy (LIPFERT, 1984; DOCKERY & POPE, 1994; ABBEY, 1999).

Chronic effects too have been demonstrated by detection of structural alterations of the lungs of individuals who live in regions with concentrations of PM. The first clear demonstration that the levels of PM promote diffuse inflammatory alterations in the respiratory tract in humans came from studies made by Souza et al (1998), wherein one detected mucosecretory hyperplasia, remodeling with fibrosis of the small airways and injury of the centroacinar region of young people who died of external causes in the metropolitan region of São Paulo. In the same study, the injuries observed were in close anatomical relationship with foci of deposition and retention of carbonaceous material (anthracosis), suggesting a cause-and-effect relationship.

In the last few decades, a great effort has been made to reduce the use of fuels derived from petroleum for generation of energy and transportation all over the world. Among the recent alternatives proposed, biodiesel, ethanol, besides blends containing biodiesel/diesel and alcohol/diesel have brought much attention for use on Diesel cycle engines, being one of the solutions, in various countries, for reduction of importation of petroleum and decrease of emission of pollutants.

Ethanol, vegetable oil and biodiesel are all derived from biomass and, unlike petroleum, they are renewable fuels. Among these fuels, combustible hydrated ethyl alcohol (CHEA/AEHC) is an interesting fuel as an alternative to diesel oil to reduce emissions of pollutants. This is because ethanol contains oxygen in its molecule, being an extremely volatile fuel, which burns as a group and because CHEA/AEHC contains water in its composition (7% by mass). These characteristics are generally favorable to good combustion (PÉREZ et al, 2006).

In this regard, many research papers are investigating the effect of adding ethanol to the formation of pollutants from diesel burning. It has been widely shown that when ethanol is added to diesel, the main benefit is the reduction of soot and particulate matter, followed by a decrease in CO. Ajav et al (1999) showed that, by incrementing the ethanol percent in the diesel mixture, the output temperature of gases and the emissions of CO and PM were reduced. Suppes (2000) analyzed the experimental results of different authors and concluded that one can effectively talk of a reduction in the particulate matter when ethanol is added to diesel. But one cannot conclude the same thing for NOx, since some researchers reported an increase in the emission thereof and other reported a decrease.

The reduction of these particulates is also pointed out in the comprehensive bibliographic revision made by Hansen et al (2005).

The use of ethanol as a fuel is advocated by many, especially because of the reduction in emissions of gases responsible for the greenhouse effect upon replacing fossil fuels. Macedo (2004) analyzed the energy balance of fossil energy consumed in the production and processing of sugar cane in comparison with the energy provided by using ethanol and with the energy generated by sugar-cane bagasse. The relationship between the renewable energy produced and the fossil energy consumed in the production of ethanol is of from 8.3 to 10.2, that is, with each unit of fossil energy spent in the ethanol production cycle, one obtains from 8.3 to 10.2 units of renewable energy.

According to Mma & Lima/coppe/ufrj (2002), alcohol virtually does not has sulfur in its composition, so the use thereof does not contribute to emission of SOx, and still its lower molecular complexity enables combustion with extremely low formation of carbon particles, which results in negligible emission of PM.

Another encouraging factor for the alcohol market is the possibility of adding ethanol to diesel. Tests have demonstrated that the use of blends of 3% ethanol to 97% diesel may be adopted on any engine without causing problems, reducing the emissions of particulate matter and other pollutants (GELLER et al, 2004; HE et al, 2003).

In Brazil, studies with the alcohol/diesel blend have been carried out ever since 1984, when it was found out that mixtures of diesel oil with anhydrous alcohol were feasible, since they did not cause loss of efficiency of the engine or increase in the consumption of fuel and brought about reduction in the emission of particulates. Thus, research works and field tests have been carried out for introduction of a program of adding ethanol to the energy matrix of diesel. (ECONOMY & ENERGY, 2001).

Generally speaking, pure vegetable oils can be used as alternative fuels. Rudolph Diesel had the idea of using groundnut oil on his engines at the Paris exhibition in 1900. However, vegetable oils have high viscosity and, in order to use them on Diesel cycle engines, without the need for adapters, one has to reduce the viscosity values to values close to that of conventional diesel (MA & HANNA, 1999; RABELO, 2003).

Somewhat more recent than ethanol, biodiesel has also found its place and has an accelerated growth on the national liquid biofuel market. But unlike ethanol, which has sugar cane as its ideal raw material, biodiesel is still at the stage of intense research and development (PNA, 2005). However, there are various papers that point to an environmental advantage in favor of biodiesel as compared with conventional diesel, a fact that puts it in the front line of the substitutes for petrodiesel.

Peterson & Reece (1996) tested methyl and ethyl esters of rapeseed on a Diesel cycle engine of Mark Cummins, on a dynamometric bench. The emissions of hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx) and particulate matter (PM) provided by vegetable oil had −52.5%, −7.6%, 0.9%, −10.0% with respect to those obtained with diesel oil, respectively.

Characteristics of the emission of pollutants in dynamometric tests with compression-ignition engine, using diesel, biodiesel and biodiesel/diesel blends (B20, B35, B65 and B100), were determined by Schumacher et al (2001). The authors observed that the emission of NOx increased, while those of HC, CO and PM decreased as the concentration of biodiesel increased.

In the same line of research, Muñoz et al (2004) tested mixtures of sunflower methyl ester and diesel (B25, B50, B75 and B100) on an automotive Diesel engine to determine the levels of emission of pollutants. In the tests carried out, the emission of hydrocarbons with the biodiesel blends was lower with respect to diesel only in some operational conditions, especially at low loads. The concentration of NOx with pure biodiesel, however, was always higher than that with diesel. Notwithstanding, the reduction of the blackening degree and of the specific emission of particulate matter measured are representative and favorable to the use of biodiesel, which, in part, is explained by the absence of sulfur in the biodiesel. Sulfur shares the oxygen available in the later phase of the combustion with carbon resulting from the partial burning, in some operational conditions of the engine, thus increasing the production of particulate matter.

According to Fernando & Hanna (2004), biodiesel has been used not only as an alternative to replace petroleum diesel, but also as an emulsifying additive to compose ternary diesel/biodiesel/alcohol blends.

In this context presented, the objective of this paper was to quantify the emission of particulate matter of ternary blends composed of alcohol, biodiesel and vegetable oil on a Diesel cycle engine, employing an identical engine operating with conventional diesel, in an attempt to demonstrate the potential of utilization of these blends as possible fuel substitute for petrodiesel.

Materials and Methods

The tests involving alternative fuel blends were carried out in the agricultural mechanization sector of the experimental unit of Embrapa Soja, in Londrina—PR, where the stationary engine and the electricity generators employed in the experimentation are allocated. For the tests, one adopted two stationary Diesel cycle and 4-stroke air-cooled engines of mark Toyama, model 70f, with direct injection and 6 HP nominal power, one of which having been supplied with only diesel oil and the other with the ternary blends containing vegetable oil/biodiesel/ethanol. This way, each engine could be evaluated individually according to the fuel employed. The main technical specification and measures of the engines are described in Table 1. In order to impart load to the engines, one has also employed a 10-KVa electric generator of mark Bambozzi, with 1.800 rpm nominal rotation, which could be utilized with the above-mentioned engine that has nominal rotation of 3,000-3,600 rpm. The transmission of mechanical energy from the Diesel engine to the generator was carried out by transmission belt and a set of pulleys coupled to both axles of the equipment.

TABLE 1 Technical specifications and measurements of the Toyama 70f Engine Item Technical specification Type 4-stroke single-cylinder Cooling Air cooling Cylinder displacement (L) 0.296 Nominal rotation (RPM) 3,000-2,600 Nominal power (HP) 5.4-6.0 Average piston velocity (m/s)  6.2-7.44 Average effective pressure (kgf/cm2) 5.52-5.07 Fuel consumption relationship <206; <215) (gHP · h) Lubricating-oil consumption relationship <3 (g/HP · h) Fuel tank capacity (L) 3.5 Direction of rotation axis Time, seen from the steering wheel Type and lubrication Oil pump Type of start Manual, retractile Net weight (kg) 33

The blends used in the experiment were composed by:

-   -   Blend 1: 60% biodiesel from soybean oil, 30% anhydrous ethanol         and 10% vegetable oil; soybean refinate;     -   Blend 2: 50% biodiesel from soybean oil, 40% anhydrous ethanol         and 10% vegetable oil; soybean refinate.

In addition to the conventional Diesel oil fuel derived from petroleum, employed on the witness-engine.

For comparison of the emission of the fuels, particulate matter from exhaust of engines was collected by using a circular filter paper with 5-cm diameter, made from fiberglass of the company Energética—Qualidade do Ar.

This material was previously dehydrated in an oven at 105° C. for elimination of the moisture existing therein. After this drying, the filters were weighed and tared on a digital precision balance, and finally installed at the end of the exhaust manifold, where they were capable of retaining the particulate matter expelled by the engine.

The working system employed was the following: the filters remained coupled to the end of the exhaust manifold for 5 minutes, time necessary to retain a sufficient amount of particles, since the filters were exposed for a longer time and there was no difference in the weights thereof.

After collection of the material, the filter papers were again dried and then led to the precision balance for assessment of the amount by mass of the particulates produced by the engines.

Results and Discussion

The results achieved by using the ternary biofuel blends indicated an expressive reduction in the level of particulate matter emitted by the engine at its maximum nominal rotation (3,600 rpm), a behavior resulting from the replacement of a fuel having a long carbon chain (diesel oil) averaging 13 carbons and a high boiling point (of 190° C. to 330° C.), by a fuel blend containing ethanol of more simple chain and of lower boiling point.

The values obtained in the experiment are presented in FIG. 5, in the form of specific mass of the material retained, at an interval of 5 minutes of collection, using a fiberglass filter.

From the above graph one can observe that, as one raises the amount of ethanol in the ternary blend, there will be a concomitant drop in the emission of particulate matter, a fact that, according to Dietrich & Bindel (1983), is explained by the presence of ethanol, which leads to an easier combustion, implying reduction in the content of unburned carbon, thus corroborating the results achieved in the experiment.

Reduction in the emission of particulates was also observed in the experiments made by Holmer et al (1980), who made replacements of up to 32% of the diesel oil by ethanol, by using microemulsion. Similar results were obtained by Goering et al (1992), who noted suppression in the emission of smoke when they used injection of ethanol into the intake manifold or into the cylinder injector. In the same line of research, Feitosa (2003) managed to achieve an expressive decrease in emission of particulates by replacing up to 50% of diesel with ethanol.

Another compound present in the blend, which was also responsible for the drop in emission of particulates, is biodiesel. Although the amount of particulate matter retained by the filter was larger by raising the concentration of biodiesel in the blends, due to the decrease in the amount of ethanol (FIG. 5), the fuel containing biodiesel present in the two blends proved to be less pollutant than conventional diesel, thus attesting the important capability of this biofuel to reduce emissions of particulates of the engine.

In the literature, various authors demonstrate the efficiency of biodiesel in reducing total particulates of the engine. Sunflower/diesel biodiesel (B25, B50, B75 and B100) were used by Muñoz et al (2004) on an automotive Diesel engine to determine the levels of emission of pollutants. The reduction of the darkening degree and of the specific emission of particulate matter measured was quite representative and favorable to the use of biodiesel, which, in part, is explained by the absence of sulfur in the biodiesel.

Sulfur shares the oxygen available in the later phase of the combustion with the carbon resulting from the partial burning, in some operational conditions of the engine, increasing the production of particulate matter (MUÑOZ et al., 2004; GRABOSKI & MCCORNICK, 1997; SHARP et al., 2000).

Stable ternary blends containing diesel/biodiesel/ethyl alcohol for feeding Diesel cycle engines were successfully prepared by Kwanchareon et al. (2006), Caetano (2003) and dos Santos (2005). In all the studies, the authors achieved positive results regarding the emission of pollutants to the atmosphere, a fact that, in times of excessive concern about preservation of the environment, proved to be an excellent alternative to the use of purely fossil fuel.

Conclusions:

-   -   The use of the biofuel ternary blends in the conditions and         methods of carrying out the experiment was efficient in reducing         the emission of particulate matter present in the exhaust gases         of the Diesel cycle engine studied.     -   The increase in the concentration of ethanol in the blend in the         conditions of carrying out the work was fundamental to the         marked drop in the emission of particulate matter.

References:

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1. Objective

Given the demand for biodiesel on the market, there has been a rise in the price of many raw materials, and so there is a search for even more economical alternatives to the production and efficient use thereof on engines. One of these alternatives is the use of ternary blends composed of vegetable oil, ethyl biodiesel and hydrated ethanol. These blends are said to have properties that would favor combustion, with cetane number, heat power and viscosity close to those of petroleum diesel or even to pure biodiesel [1]. In this context, the objective of this work was to compare the miscibility of ternary blends of these three components for use on diesel cycle engines.

2. Materials and Methods

The biodiesel was produced at the UNAERP from refined soybean oil, anhydrous ethyl alcohol and sodium hydroxide, as a homogeneous catalyst. The resulting biodiesel was washed with water and evaporated to eliminate glycerin, fatty acidic soaps and residual moisture. The ternary blends were prepared at proportions ranging from 0 to 100% by mass of each component, in 10-mL test tubes. After mechanical stirring for a few minutes, the tubes were centrifuged, and the miscibility of the phases was verified by visual inspection. Two vegetable oils were tested: soybean oil and castor oil. The tests were conducted at 3 different temperatures: 10° C., 25° C. and 50° C.

3. Results

The miscibility maps obtained in this work are shown in FIG. 1. Such miscibility maps refer to the ternary blends at different temperatures. Yellow points mean miscible blends and red points mean immiscible blends.

4. Conclusion

The hydroxyl group situated on the carbon 12 present in the ricinolein (the main fatty acid of castor bean) imparted to castor oil the greatest tendency to solubility in the blends studied as compared with soybean oil. The rise in temperature also resulted in a larger number of miscible blends.

5. Bibliographic Reference

-   [1] P. Kwanchareon et al., Solubility of a diesel-biodiesel-ethanol     blend, its fuel properties, and its emission characteristics from     diesel engine. Fuel 86 (2007) 1053-106. 

1. A fuel for feeding Diesel cycle engines, characterized by having the following composition: (i) lower alcohol in the proportion range from 10% to 50% by mass; (ii) vegetable oil in the proportion range from 10% to 60% by mass; and (iii) ethyl or methyl ester (biodiesel) in the proportion range from 20% to 80% by mass.
 2. The fuel for feeding Diesel cycle engines according to claim 1, characterized by presenting anhydrous alcohol in the form of ethanol, preferably of the anhydrous type.
 3. The fuel for feeding Diesel cycle engines according to claim 1, characterized by presenting anhydrous alcohol in the form of methanol, preferably of the anhydrous type.
 4. A fuel for feeding Diesel cycle engines characterized by having the following composition: i. lower alcohol, preferably anhydrous, in the proportion range from 10% to 50% by mass; ii. vegetable oil in the proportion range from 10% to 60% by mass; and iii. petrodiesel, biodiesel or any mixture thereof in the proportion range from 20% to 80% by mass.
 5. A fuel for feeding Diesel cycle engines, characterized by having the fuel composition according to claim 1, mixed with petrodiesel in any proportion. 